GSK (LSE:GSK) on Monday announced that interim results from its phase II AZUR-1 trial show that 76% of evaluable patients with stage II and III MSI-H/dMMR locally advanced rectal cancer achieved a complete response to Jemperli (dostarlimab) monotherapy alone.
The London-listed drugmaker's exploratory analysis covered 110 of 144 evaluable patients, with a 95% confidence interval of 69% to 83%.
Within that group, 68% reached a sustained clinical complete response of at least 12 months without surgery, as assessed by investigators, while a further 12 patients had their complete response confirmed through tissue analysis after surgery showed no evidence of cancer.
No disease recurrences have been reported among responders after a median follow-up of more than two years, according to GSK.
The data supported the recent US approval of Jemperli in this indication, which GSK disclosed on 19 October as an FDA accelerated approval for stage II/III MSI-H/dMMR locally advanced rectal cancer.
On the trial's primary endpoint, measured by independent central review, 47% of evaluable patients (54 of 116) achieved a sustained clinical complete response of 12 months, with a confidence interval of 37% to 56%; GSK said this data continues to mature, with a further 38 participants having already reached clinical complete response but not yet the 12-month assessment point.
"The AZUR-1 data demonstrate the potential for Jemperli alone to transform treatment for eligible patients with MSI-H/dMMR locally advanced rectal cancer," said Hesham Abdullah, senior vice president and global head of oncology R&D at GSK, adding that avoiding chemotherapy, radiation and surgery "may now be possible" for some patients.
Andrea Cercek, principal investigator of AZUR-1 and section head of colorectal cancer at Memorial Sloan Kettering Cancer Center, said the absence of recurrences after more than two years "should provide physicians with confidence in an organ preservation approach in this patient population."
Read more about GSK
- 19/10/26GSK wins first US approval for Jemperli in rectal cancer
- 24/08/26FDA grants priority review to GSK's Jemperli for rectal cancer
- 13/07/26GSK's Jemperli hits primary goal in rectal cancer trial
Serious adverse reactions occurred in 20% of patients receiving Jemperli, with the most common adverse reactions being fatigue, rash, diarrhoea and pruritus; the drug was permanently discontinued due to adverse reactions in 3% of patients.
Jemperli is a PD-1-blocking antibody that GSK licenses from AnaptysBio under an agreement originally signed by TESARO, now a GSK subsidiary, in March 2014.
Regulatory reviews are continuing in participating countries through Project Orbis, the FDA Oncology Center of Excellence initiative that enables concurrent review by international health authorities, and the findings will be presented in a late-breaking oral session at the European Society for Medical Oncology Congress.